Pre-fastened rail pad assembly and method

ABSTRACT

A rail pad assembly and an associated method for use with a concrete rail tie. The assembly includes rail pad for engagement with a metal rail and a protective sheet for interposition between the rail pad and the tie. The rail pad is releasably attachable to the sheet such that releasing attachment occurs without destruction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No. 10/924,517 filed Aug. 24, 2004.

FIELD OF THE INVENTION

The present invention relates to the field of rail pad assemblies for railway systems that have metal rails and concrete rail ties.

BACKGROUND OF THE INVENTION

Railway systems commonly seat a metal rail upon a concrete rail tie via the use of a rail pad. There is a well-known problem of abrasion that can occur between a rail pad and a concrete rail tie.

Generally, a rail pad deflects vertically and horizontally in a cyclic fashion under the loads imposed by the wheels of passing trains. The cyclical loads imposed upon the rail pad create relatively short-term vertical load pulses that cause the face of the rail pad to oscillate on the concrete tie. Deterioration of the rail pad and erosion of the concrete rail tie can occur. It is known to use a protective member or sheet located between the rail pad and the concrete rail tie to prevent deterioration. The rail pad and the protective sheet can be considered to be the major parts of a rail pad assembly. However, the handling of the various components of a rail pad assembly is often labor intensive and/or otherwise problematic.

SUMMARY OF THE INVENTION

In accordance with one aspect, the present invention provides a rail pad assembly for use with a concrete rail tie. The assembly includes a rail pad for engagement with a metal rail and a protective sheet for interposition between the rail pad and the concrete rail tie. The assembly also includes means for releasably attaching the rail pad to the sheet integrally formed in at least one of the rail pad and the sheet and releasing attachment without destruction of any portion of the means for releasably attaching.

In accordance with another aspect, the present invention provides a method of releasably assembling a rail pad assembly for use with a concrete rail tie. The method includes providing a rail pad for engagement with a metal rail, providing a protective sheet for interposition between the rail pad and the concrete rail tie, and providing means for attaching the rail pad to the sheet integrally formed in at least one of the rail pad and the sheet prior to attaching the rail pad to the sheet. The method also includes attaching the rail pad to the sheet using the means for attaching, and releasing the rail pad from the sheet without destruction of any portion of the rail pad or the sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings wherein:

FIG. 1 is a section view of an example rail pad assembly, which has a rail pad and a protective sheet, between a metal rail and a concrete rail tie;

FIG. 2 is a top view of the rail pad of the assembly of FIG. 1;

FIG. 3 is a sectional view of the rail pad taken along line 3-3 of FIG. 2;

FIG. 4 is a top view of the protective sheet of the assembly of FIG. 1;

FIG. 5 is a sectional view of the protective sheet taken along line 5-5 of FIG. 4;

FIG. 6 is an enlarged, plan view of a portion of the assembly of FIG. 1;

FIG. 7 a is an enlarged, sectional view of the rail pad assembly taken along line 7 a-7 a of FIG. 6;

FIG. 7 b is a view similar to FIG. 7 a, but shows an alternate construction that includes a ridged, ringed, or threaded connection; and

FIG. 7 c is a view similar to FIG. 7 a, but shows another alternate construction that includes a rivet connection.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Referring initially to FIG. 1 of the drawings, a rail pad assembly 8 is shown for use with a metal rail 14 and a concrete rail tie 16. The rail pad assembly 8 includes a rail pad 10 and an attached protective sheet 12. It is to be appreciated that the attached aspect provides a pre-fastened assembly that provides for ease of handling, etc. during transport, installation, etc. As shown in an example embodiment in FIG. 1, the metal rail 14 sits atop the rail pad 10, and the protective sheet 12 is located between the rail pad 10 and the concrete rail tie 16. It is to be appreciated that additional components and/or material may also be interposed between the rail pad 10 and the concrete rail tie 16. The metal rail 14 is held in place by rail clamps (not shown) embedded in the concrete rail tie 16. Such rail clamps may take various forms, including various currently available forms, but are not limitations on the present invention.

Turning now to FIG. 2., the example rail pad 10 is shown in detail. In one example, the rail pad 10 is made of an elastomeric material, such as polyurethane or ethylene vinyl acetate (EVA). The rail pad 10 is generally rectangular or square, but it is to be appreciated that the rail pad 10 can be of any suitable shape. Turning briefly to FIG. 3, the rail pad 10 has a top surface 18 and a bottom surface 20. Turning back to FIG. 2, the top surface 18 of the rail pad 10 includes at least one rail-engaging area 28 having a tread pattern. In the example shown in FIG. 2, the top surface 18 includes three rail-engaging areas 28 having identical tread patterns. It is to be appreciated that the top surface 18 of the rail pad 10 may include any number of such areas 28, each having any tread pattern. Although the configuration of such features of the rail pad 10 is described for the purpose of comprehending the drawings, such configuration is not a limitation on the present invention.

As shown in the example of FIG. 2, the rail pad 10 has a generally square or rectangular outer periphery 31. The rail pad also includes various indentations and notches 30 along its outer periphery 31 for engagement with, and/or accommodation of, structure located along the railway system, such as the rail clamps (not shown). Such notches 30 are located between upwardly extending projections that are located on the sides of the rail 14 and seat the rail onto the rail pad 10. It is to be appreciated that the geometry of the rail pad 10 may be varied in any manner required by a particular railway system, and such features are not limitations on the present invention.

In the example shown in FIG. 2, the rail pad 10 also includes at least one passageway 22 extending therein as part of a configuration for attaching the rail pad 10 to the protective sheet 12. It is to be appreciated that the rail pad 10 may include any number of passageways 22 that may or may not extend completely through the rail pad 10. In the example shown in FIG. 3, the passageways 22 comprise four holes extending from the top surface 18 of the rail pad to the bottom surface 20. Each passageway 22 is countersunk within the rail pad 10 such that the upper portion 24 of each passageway 22 has a diameter greater than the lower portion 26 of each passageway 22. The difference in diameter between the upper portion 24 and the lower portion 26 of each passageway 22 creates a circular shoulder 27 within each passageway 22 at the interface of the upper portion 24 and the lower portion 26. It is to be appreciated that the passageways 22 may be of any size, shape, number, geometry, and position.

Turning now to FIG. 4, the example protective sheet 12 is shown in detail. In one example, the protective sheet 12 is made of tough and abrasion resistant material, such as ultrahigh molecular weight polyethylene (UHMWPE). One example of UHMWPE is a polyethylene (e.g., linear) with a molecular weight in the range of 3,000,000 to 6,000,000. Other more specific examples of UHMWPE may have molecular weight ranges bounded by the numbers 4,000,000 and/or 5,000,000. Although one aspect of the present invention includes the use of UHMWPE, it is to be appreciated that other materials that offer beneficial characteristics, such as abrasion resistance and/or impact strength, may be used for the protective sheet 12 in accordance with other aspects of the present invention. It is to be appreciated that the protective sheet 12, with the structures described herein, may be made by any process including, but not limited to a process that includes injection forming, compression forming, or injection and compression forming.

Turning briefly to FIG. 5, the protective sheet 12 has a top major surface 32 and a bottom major surface 34. The top surface 32 and the bottom surface 34 of the protective sheet 12 are substantially flat. However, it is to be appreciated that the contours of the top surface 32 and/or the bottom surface 34 are not limitations on the present invention. As shown in FIG. 6, the outer periphery shape of the protective sheet 12 is generally similar to the outer periphery shape of the rail pad 10. That is to say that the shown example of the protective sheet 12 has a generally rectangular or square shaped outer periphery, but it is to be appreciated that the protective sheet 12 can be of any suitable shape.

As shown in the example of FIG. 4, the protective sheet 12 also includes various indentations and notches 44 along its outer periphery 45 for engagement with, and/or accommodation of, structure located along the railway system, such as the rail clamps (mentioned above). It is to be appreciated that the outer geometry of the protective sheet 12 may be varied in any manner as required by a particular railway system, and is not a limitation on the present invention.

In the example shown in FIG. 4, the protective sheet 12 also includes at least one projection 36 extending from the top surface 32 to extend into a passageway 22, as means for attaching the protective sheet 12 to the rail pad 10. It is to be appreciated that the protective sheet 12 may include any number of projections that extend into corresponding passageways 22. In the example shown in FIG. 5, four projections 36 are integrally formed as part of the protective sheet 12 and extend from the top surface 32 thereof. The projections 36 have a first end 37 attached at the top surface 32 of the protective sheet 12 and a second end 38 located at a distance from the top surface 32. The second end 38 has a relatively larger cross-sectional area due to a cutout portion 40, which adjacent to the first end 37, and located between the top surface 32 and the second end 38 of the projection 36. In the example shown in FIG. 5, the cutout portions 40 of the two projections 36 located on the left half of the protective sheet 12 face a direction opposite the cutout portions 40 of the two projections 36 located on the right half of the protective sheet 12. Additionally, the second end 38 of each projection may include a chamfered edge 46 to facilitate ingress of the projection 36 into a mating passageway. However, it is to be appreciated that the projections 36, including the cutout portions 40, may be of any size, shape, number, geometry and position. Furthermore, a passageway 42 may be positioned adjacent to the projection 36 and may extend though the protective sheet 12. This passageway 42 may facilitate formation.

Turning now to FIG. 6, the rail pad 10 is shown attached to the protective sheet 12 to form the rail pad assembly 8. The various indentations and notches 30 along the outer periphery 31 of the rail pad 10 are generally aligned with the various indentations and notches 44 along the outer periphery 45 of the protective sheet 12. In the example shown in FIG. 6, the longitudinal dimension of the protective sheet 12 is greater than the longitudinal dimension of the rail pad 10. However, it is to be appreciated that the dimensions of the rail pad 10 and the protective sheet 12 may be varied in any manner as required by a particular railway system.

In the example shown in FIG. 7a, each passageway 22 of the rail pad 10 receives a respective projection 36 of the protective sheet 12 for a snap-fit interconnection. The projection 36 is inserted through the lower portion 26 of the passageway 22 and into the upper portion 24 of the passageway 22 until the bottom surface 20 of the rail pad 10 engages the top surface 32 of the protective sheet 12. The snap-fit interconnection is created by an interaction between-the cutout portion 40 of the projection 36 and the circular shoulder 27 within the passageway 22 formed by the difference in diameter between the upper portion 24 and the lower portion 26 thereof. The snap-fit interconnection ensures that the rail pad 10 remains attached to the protective sheet 12, and also allows for easy maintenance or replacement of the parts because the connection is reversible via application of a modest amount of separating force. It is to be appreciated that the drawing figures may show the dimensions of the projections 36 and the passageways 22 some what exaggerated to convey the concept. It is also to be appreciated that the interconnection may take various other forms. For example, the projections 36 and passageways 22 may provide for a friction or interference fit. In fact, the shown example, is to be understood to be one type of interference fit.

It of course is to be appreciated that the interference fit avoids the need to use separate fastener(s). Also, it is to be appreciated that the interference fit avoids the need to perform a separate fastening step, such as gluing, welding, or melting any parts. Still further, it is to be appreciated that the interference fit avoids the need to change or destroy any structure. For example, the projections 36 need not be broken off or melted to permit removal. Thus, the rail pad 10 remains attached to the protective sheet 12 and yet the attachment is reversible via a non-damaging amount of separating force. It is to be appreciated that tremendous labor saving is likely to be realized.

Also, the Figures show one example aspect that the projections 36 are at locations that are beneath an engagement interface between the rail pad and the rail, such that the rail does not engage the projection. One way of viewing this is that the rail pad, the sheet, and the projection and the opening are configured such that when the rail pad and the sheet are attached together the projection extends into the opening from the first side but does not extend beyond the second side. This due to the size of the projections 36 being such that no part of the projections extend above the rail pad. This helps to avoid undesirable damage to the projections 36. Specifically, breakage of upper portions of the projections can be avoided. Moreover, the rail actually covers the projections. Of course, different projection locations and heights are contemplated.

In another example of the rail pad assembly 8 shown in FIG. 7 b, at least one projection 36 may be ridged, ringed, or threaded and at least one passageway 22 may be adapted to receive the ridged, ringed, or threaded projection 36. In this example, the projection 36 includes ridges, rings, or threads 50 that engage with ridges, rings, or threads 48 disposed on the interior surface of the passageway 22 to form a retaining connection.

In yet another example of the rail pad assembly 8 shown in FIG. 7 c, at least one projection 36 may comprise a rivet-like structure 54 and at least one passageway 22 may be adapted to receive the rivet-like structure. In this example, the projection includes a first end 51 and a second end 52 extending a distance from the first end 51, wherein the diameter of the second end 52 is greater than the diameter of the first end 51 to form a rivet-like structure 54. The diameter of the second end 52 is also greater than the diameter of the passageway 22. A rivet-like interconnection is created by inserting the second end 52 of the projection 36 through the passageway 22 until the bottom surface 20 of the rail pad 10 mates and engages the top surface 32 of the protective sheet 12. The top of the rivet-like structure may deflect during insertion. Of course, it is to be appreciated that dimensions may be exaggerated to show the concept.

It is to be appreciated that any projection 36 may be adapted to any passageway 22 to ensure that the rail pad 10 is attached to the protective sheet 12 to make handling, etc. easier. Accordingly, it is also to be appreciated that the rail pad 10 may include any number of projections, and the protective sheet 12 may include any number of passageways, in a fashion similar to that disclosed herein. Of course, it is to be appreciated that the projections and the passageways may be reversed between the rail pad la and the protective sheet 12 (i.e., projections extending from the rail pad). Also, other types of integrally-formed, attaching/retaining elements on the pad and sheet are contemplated to be within the scope of the present invention. As such, it is to be appreciated that the present invention provides means to attach the rail pad 10 and the protective sheet 12, which does not require separate attachment components, devices, etc. For example, pieces of adhesive tape extending to secure the protective sheet to the rail pad and are not needed.

The present invention also includes a method of assembling a rail pad assembly 8 for use with a concrete rail tie 16. In one example consideration, first, a rail pad 10 is provided for engagement with a metal rail 14. Next, a protective sheet 12 is provided for interposition between the rail pad 10 and a concrete rail tie 16. Next, means for attaching the rail pad 10 to the protective sheet 12 are provided. The means for attaching are integrally formed in at least one of the rail pad 10 and the protective sheet 12. Finally, the rail pad 10 is attached to the protective sheet 12 using the means for attaching. In another example consideration, the method includes providing the rail pad 10 for engagement with the metal rail 14, providing the protective sheet 12 for interposition between the rail pad and the concrete rail tie; and providing the means for attaching the rail pad to the sheet integrally formed in at least one of the rail pad and the sheet prior to attaching the rail pad to the sheet. The method also includes attaching the rail pad 10 to the sheet 12 using the means for attaching, and releasing the rail pad from the sheet without destruction of any portion of the rail pad or the sheet. It is to be appreciated that the steps of these example method may be performed in any order, and that additional steps may be incorporated into this example method as required.

It is to be understood that the invention has been described with regard to certain example embodiments. It is to be appreciated that certain modifications, changes, adaptations, etc., are contemplated and considered within the scope of the appended claims. 

1. A rail pad assembly for use with a concrete rail tie, including: a rail pad for engagement with a metal rail; a protective sheet for interposition between the rail pad and the concrete rail tie; and means for releasably attaching the rail pad to the sheet integrally formed in at least one of the rail pad and the sheet and releasing attachment without destruction of any portion of the means for releasably attaching.
 2. The rail pad assembly of claim 1, wherein the means for releasably attaching includes means for releasing the rail pad from the sheet without changing any structure of either the rail pad from the sheet.
 3. The rail pad assembly of claim 2, wherein the means for releasably attaching the rail pad to the sheet includes a projection, and the means for releasing the rail pad from the sheet without changing any structure includes means for releasing that does not include melting or removal of any portion of the rail pad and the sheet.
 4. The rail pad assembly of claim 2, wherein the means for releasably attaching includes means for reattaching the rail pad and the sheet without changing any structure of either the rail pad from the sheet.
 5. The rail pad assembly of claim 2, wherein the means for releasably attaching the rail pad to the sheet includes a projection on one of the rail pad and the sheet and a passageway between two sides of the other of the rail pad and the sheet, the passageway is adapted to receive the projection for an interference fit connection such that the connection is reversible via a non-damaging amount of separating force.
 6. The rail pad assembly of claim 2, wherein the means for releasably attaching the rail pad to the sheet includes a projection on one of the rail pad and the sheet and a passageway between two sides of the other of the rail pad and the sheet, the rail pad, the sheet, and the projection and the opening are configured such that when the rail pad and the sheet are attached together the projection extends into the opening from the first side but does not extend beyond the second side.
 7. The rail pad assembly of claim 6, wherein the projection and the passageway are on the rail pad and the sheet at locations that are beneath an engagement interface between the rail pad and the rail, such that the rail does not engage the projection.
 8. The rail pad assembly of claim 1, wherein the means for releasably attaching includes at least one projection on at least one of the rail pad and the sheet, and at least one passageway extending in at least one of the rail pad and the sheet, and the projection and the passageway having an interference fit relationship.
 9. The rail pad assembly of claim 8, wherein the interference fit relationship provides a holding force that retains the rail pad and the sheet together, and the holding force can be overcome with force large enough to separate the rail pad from the sheet but not large enough to damage any portion of the rail pad or the sheet.
 10. The rail pad assembly of claim 1, wherein the means for releasably attaching includes a plurality of projections on at least one of the rail pad and the sheet, and a corresponding plurality of passageways extending in at least one of the rail pad and the sheet for receiving the projections, and all of the projections being located along a single line.
 11. A method of releasably assembling a rail pad assembly for use with a concrete rail tie, including the steps of: providing a rail pad for engagement with a metal rail; providing a protective sheet for interposition between the rail pad and the concrete rail tie; providing means for attaching the rail pad to the sheet integrally formed in at least one of the rail pad and the sheet prior to attaching the rail pad to the sheet; attaching the rail pad to the sheet using the means for attaching; and releasing the rail pad from the sheet without destruction of any portion of the rail pad or the sheet.
 12. The method of claim 11, wherein the step of releasing the rail pad from the sheet includes releasing the rail pad from the sheet without changing any structure of either the rail pad from the sheet.
 13. The method of claim 12, wherein the step of releasing the rail pad from the sheet includes releasing that does not include melting or removal of any portion of the projection.
 14. The method of claim 12, wherein the step of providing means for attaching the rail pad to the sheet includes providing at least one projection on at least one of the rail pad and the sheet and at least one passageway extending through at least the other of the rail pad and the sheet, and the step of attaching the rail pad to the sheet includes inserting the projection into the passageway in an interference fit relationship.
 15. The method of claim 11, wherein the step of attaching the rail pad to the sheet using the means for attaching includes attaching the rail pad to the sheet without changing any structure of either the rail pad of the sheet.
 16. The method of claim 15, wherein the step of attaching the rail pad to the sheet includes a snap-fit interconnection of portions of the rail pad and the sheet.
 17. The method of claim 11, wherein step of releasing the rail pad from the sheet is via application of a modest amount of separating force.
 18. The method of claim 11, wherein the rail pad has a surface upon which the rail is to be seated, and the step of providing means for attaching the rail pad to the sheet includes providing means for attaching located such that the means for attaching is located directly under the rail when the rail is seated on the rail pad.
 19. The method of claim 18, wherein the means for attaching includes a projection is located entirely below the surface upon which the rail is to be seated. 